[FIX] web_tour: adapt tip color to new brand color

Since commit 8ac1c19fac7615fecd51e670f798d13158a4e53c the odoo brand primary color
changed, which also changed the color of tips. The problem
was that they lose a lot of contrast in the appswitcher.

addons/web_tour/static/src/less/tip.less

@@ -4,7 +4,7 @@
 }
 
 .o_tooltip {
-    @o-tip-color: lighten(@odoo-brand-primary, 10%);
+    @o-tip-color: @odoo-brand-primary;
     @o-tip-size: 24px;
     @o-tip-border-width: 2px;
     @o-tip-arrow-length: 10px;